1. Field of the Invention
This invention relates generally to detergent dispensing systems and more particularly to a detergent dispensing system for automatically converting powdered detergent within a container into a concentrated detergent solution for maintaining a predetermined volume of the solution available for use.
2. Description of the Prior Art
Washing machines used in industrial applications such as in restaurants, laundries, car washes and other institutionalized applications, typically include a holding tank which forms an integral part of the washing apparatus proper, for holding a detergent solution available for use and/or recirculation within the washing machine as required by the various washing cycles thereof. These types of washing machines typically run on a continual basis and it is necessary to periodically add detergent to the holding tank as the detergent solution is used or becomes diluted during washing operations. It has become commonplace for a concentraton regulating apparatus to be used for maintaining the detergent concentration level within the holding tank at a predetermined strength. The regulating apparatus generally includes level sensing means and a conductivity cell within the holding tank for providing output control signals to maintain the volume level and concentration strength respectively of the detergent solution within the holding tank at predetermined valves.
The detergent for supplying such industrial washing machines and particularly with respect to industrial dishwashing machines and industrial conveyor-type washing machines, is typically purchased in powdered form housed in cylindrical shipping containers either in larger 30 gallon sizes or in easier-to-handle 5 to 10 gallon sizes. Since these washing machines consume large quantities of detergent, thus requiring frequent recharging of the detergent feeding apparatus, it has become commonplace to supply the holding tank with concentrated detergent solution from detergent dispensers which are remotely located from the washing machine proper. Such remotely located detergent dispensers can conveniently be positioned near the supply of washing detergent and can be rapidly loaded and unloaded without disrupting the operations of the washing machine proper and without interfering with the activities of the staff attending to or working adjacent the washing machine proper. Use of remotely located detergent dispensers also facilitates maintenance and repairs of both the detergent dispenser apparatus and the washing machine proper.
A plurality of such remote powdered detergent dispensers have appeared in the prior art. The practical embodiments of such dispensers have typically positioned the detergent bearing container in inverted manner over an underlying reservoir suitable for maintaining a predetermined volume of concentrated detergent solution available for supplying the holding tank of the washing machine proper. A screen having mesh sufficiently small to prevent dry powder from sifting therethrough is placed between the open end of the container and the underlying reservoir. Various spray nozzle jet configurations have been devised for directing water or solution jets or sprays through the screen into wetting engagement with the detergent carried thereby, causing saturated detergent solution to fall through the screen and into the underlying reservoir. One such early prior art design used a flat screen with a 12-jet manifold strategically positioned therebelow for directing a spray of water against the entire bottom surface of the screen. This combination proved to be unsatisfactory for commercial usage since it resulted in channeling of the detergent in the container, causing excess hydration and caking. A desirable system will not form channels within the powdered detergent, but will cause even hydration of the powdered detergent for a distance of approximately one-half inch above the retaining screen. Such low-wetting penetration into the detergent is particularly important when using powdered detergents containing active chlorine, since much of the chlorine contained in such detergent is lost through decomposition once the detergent is wetted. The composition and concentration of the detergent solution produced by the above described prior art technique significantly varied with the amount of detergent remaining within the container. The channeling inherent with that technique also permitted undesirable caking at distances well above the retaining screen, making it difficult to completely dissolve the detergent within the container and resulting in significant waste of the detergent.
Another prior art design, owned by the assignee of this invention, and described in the U.S. Pat. No. 3,595,438 to Daley et al, solved a majority of the problems of prior designs in the art by providing a curved screen between the container and the underlying reservoir which is positioned to extend into the container for supporting the powdered detergent thereabove. The Daley apparatus uses a single nozzle disposed below the curved screen for directing a low-pressure spray of water of sufficient size to cover the entire downwardly facing surface of the screen. The spray nozzle is cooperatively aligned with the screen member such that each droplet of water from the spray impinges upon the screen member in a direction generally perpendicular thereto. With the Daley apparatus, virtually no channeling of the powdered detergent occurs, and approximately only one-half inch of the powdered detergent overlying the screen is hydrated by the spray. This apparatus also provides for even use distribution of the detergent, thus eliminating practically all waste thereof. However, since plain water is sprayed from the nozzle, the Daley apparatus is susceptible to limited flushing action of the detergent cake which forms immediately above the curved screen, causing potentially wide variances in the concentration level of the detergent solution produced by such flushing action.
Another detergent dispenser apparatus attempting to improve upon the Daley apparatus, is disclosed in U.S. Pat. No. 3,850,344 to Burge et al. This apparatus employs a flat screen overlying a perforated flat support plate, which combination supports the powdered detergent within an inverted container. A single high velocity jet stream of concentrated solution from the underlying reservoir is directed through a hole formed through the center of the supportive plate and screen such that the stream passes only into the center of the powdered detergent mass within the container. The jet stream forms a channel passing entirely through the detergent mass along the longitudinal central axis of the container and is redirected back from the bottom of the inverted container into the underlying detergent mass. This action results in hydration of substantially the entire contents of the powdered detergent, with the redirected stream falling by gravity through the screen and perforated supportive plate into the underlying reservoir. The Burge type of apparatus is limited in its application to use with those powdered detergents which do not contain chlorine, since the chlorine is decomposed in the powdered detergent mass in a relatively short time following the initial wetting of the detergent mass when such an apparatus is employed.
Notably lacking from the prior art remote detergent dispensing systems is such an apparatus that can be flexibly used to reliably dispense powdered detergents of any consistency and composition in a manner that produces highly concentrated detergent solutions of uniform composition throughout the conversion of the entire contents of a detergent holding container, and which minimizes waste due to unusable residues remaining in the dispensing container. Also notably lacking from the prior art devices is the provision therein of automatic safety features, particularly in those apparatus which direct under force highly caustic concentrated detergent solutions which can be extremely hazardous to an operator if accidently directed at his face during the removal of the spent container from the apparatus. Such safety features become of particular concern for those systems which use the easy to handle 5 to 10 gallon detergent holding containers, which an operator can maneuver out of operative position overlying the reservoir so rapidly that he may inadvertently neglect to manually secure the apparatus against any potentially hazardous conditions prior to proceeding with his unloading and loading operations.
The present invention overcomes the above-mentioned shortcomings of the prior art remote powdered detergent dispensers. The remote detergent dispenser of the present invention provides a safe and reliable method of producing highly concentrated detergent solutions for use by remotely located washing machines, produces solutions which are of substantially uniform composition and concentration throughout the conversion of the entire contents of the detergent holding container, and minimizes waste due to unusable residues remaining in the dispensing container. Further, the present invention incorporates built-in safety features which automatically protect an operator from hazardous highly caustic sprays during his unloading and loading of the apparatus.